The present invention relates to a storage system and recovery method thereof. In particular, the present invention relates to a data back-up and recovery method for a storage system containing a plurality of storage apparatus.
A method using snapshots of a set of data volumes used by applications to save data and a journal of data written to the data volumes is well-known as a method for backing up (saving) and recovering (restoring) data in a storage system, and this is typically referred to as CDP (Continuous Data Protection) etc.
For example, a typical method using snapshots and a journal is disclosed in Japanese Patent Laid-open Publication No. 2005-18738. In Japanese Patent Laid-open Publication No. 2005-18738, journals are made and accumulated every time a storage apparatus writes data of a host computer to a data volume, and then snapshots of the data volume are acquired at appropriate intervals by the storage apparatus. At the time of recovery, data (a volume image of recovery data, or simply a recovery image) held in a data volume at a specific time specified by an administrator is reproduced using a journal and snapshot that has acquired this data.
Further, technology relating to journal groups as units for reproducing this kind of recovery image is disclosed. This is a management unit where a plurality of data volumes for storage apparatus used by applications is grouped and managed as one, with the plurality of data volumes then being recovered as a group.
Typically, an application saves data by using several data volumes. Because of this, it is necessary to reproduce a recovery image at the same time with respect to a group of data volumes used by an application rather than reproducing recovery image for different times each individual data volume.
In the disclosed journal group technology, a plurality of data volumes contained in a single storage apparatus are grouped and a recovery image for a specific point in time with respect to this plurality of data volumes is reproduced.
Further, in Japanese Patent Laid-open Publication No. 2005-18738, a method of using “target time” is disclosed as a method of designating a specific time for a recovery image. This is a recovery method where an administrator designates a specific time in the past as a specific time at the time of recovery.
In this recovery method, data held in the data volume group can be reproduced from a recovery image by designating a time (hereinafter referred to as a Check Point (CP)) of writing specific data to the data volume group recognized by the application. Further, in this recovery method, data held in the data volume group can be reproduced from the recovery image by designating the time.
This is because, at the time of normal operation, applications, other programs capable of recognizing the application CP or users typically notify the storage apparatus of CP via programs controlling the storage apparatus. Further, the storage apparatus stores CP as special entries of accumulated journals. There is also a method for the administrator to designate the CP at the time of recovery. In this method, data held by the data volume group at a time of being notified of the designated CP can be reproduced from a recovery image.
However, with the storage system described above, it is possible to reproduce a recovery image at a specific time with respect to a plurality of data volumes contained in a single storage apparatus but in the even that an application uses a plurality of data volumes contained in a plurality of storage apparatus, it is not possible to acquire a recovery image for a specific time with respect to a data volume group spanning this plurality of storage apparatus.
Here, providing it is possible to acquire and manage as a group recovery image for a specific time with respect to a data volume group spanning a plurality of storage apparatus is acquired, it is possible to reproduce a recovery image for a specific time with respect to a data volume group spanning a plurality of storage apparatus and therefore provide a storage system with markedly higher operability by ordering the recovery image for the data group at a specific time to plurality of storage apparatus as a group.